HIGLEY and BOND: CHINOOK SALMON IN A RESERVOIR 



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MIGRATION OF SALMON 

 FROM RESERVOIR 



Intrinsic factors suggested as influencing 

 the downstream migration of salmonid juveniles 

 include size and age of fish (Elson, 1957) al- 

 though these apparently are variable in migra- 

 ting spring Chinook salmon juveniles (Wallis, 

 1968; Wagner, Conte, and Fessler, 1969). 

 Changes in water flow and temperature may 

 be associated with movements. Wallis (1968) in 

 reviewing literature concerning this subject 

 found a number of authors who cited elevations 

 in water temperature as correlated with down- 

 stream movements of Pacific salmon smolts. 

 Emigration of sockeye salmon juveniles from 

 Cultus and other lakes typically follows ice 

 break up and rising temperatures (Foerster, 

 1968). 



Migrants from Happy Valley Reservoir 

 varied in size from 25 to 188.9 g and included 

 fish of both age class I and class II (Table 4). 

 The migrants appeared similar in size and con- 

 dition to fish taken from the reservoir for 

 growth studies. Migrations occurred between 

 Febioiary and May of 1962 and 1963 at varying 

 temperatures and outflow volumes. In 1962, no 

 temperature relation was evident; but migra- 

 tions in 1963 occurred only at temperatures 

 above 10°C. 



In 1962, 196 fish of age class I emigrated. 

 On different days during a 6-wk period, groups 

 of 30, 37, and 33 left when temperatures were 

 3.5° to 5°C, and outflows were 0.141 to 0.283 

 m3/s (5 to 10 cfs). During an 18-day period 

 when temperatures were increasing from 6° 

 to 15 °C and outflows were less than 0.056 m^/s 

 (2 cfs), migrations of 5 to 15 fish occurred on 

 7 nights. Outflow through the iron tube, used 

 on 13 days when temperatures were 11.5° to 

 24°C, attracted one migration of 17 fish at a 

 temperature of 13°C. 



In 1963, a mid-Febmary to mid-March spill 

 volume of 0.141 m^/s (5 cfs) maximum, at tem- 

 l)eratures below 5°C, brought no migration. 

 By late April, water temperatures were 10° 

 to 13°C, and a new spill of 0.141 to 0.283 ms/s 

 (5 to 10 cfs) occurred. Aj^proximately 500 

 salmon including both age classes exited. An 

 additional 56 age class II and 498 age class I 



889 



